Instrumentation and techniques of high resolution mass spectrometry are being developed and employed for studying problems of identification, structure, and biosynthesis. These techniques include field desorption mass spectrometry (at high and low resolution), especially at high masses; gas chromatography-mass spectrometry at high and low resolution, employing capillary as well as conventional columns; and electron impact, field ionization and chemical ionization. Special attention is directed toward biologically active marine natural products, peptides (especially antibiotics), and polyene antibiotics.